Following DjLizard's help in this topic http://forum.CCleaner.com/index.php?showtopic=844
he has asked me to post about this here, so here I am.
Not sure what info you need so if you need more please do tell me what you require.
Basically after running CCleaner and clearing out everything including the registry issues I could no longer access my Yahoo emails using Firefox.
After signing in I just got a completely blank, white screen.
Now with DjLizard's help I can do this although the page layout is incomplete.
Hope this helps and please do ask for any further information that may assist.